package org.glvnsjc.util;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.ResourceBundle;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.glvnsjc.Constants;
import org.springframework.context.i18n.LocaleContextHolder;

/**
 * Date Utility Class used to convert Strings to Dates and Timestamps
 * 
 * @author <a href="mailto:matt@raibledesigns.com">Matt Raible</a>
 *  Modified by <a href="mailto:dan@getrolling.com">Dan Kibler </a> 
 *  to correct time pattern. Minutes should be mm not MM (MM is month). 
 */
public class DateUtil
{
    private static Log log = LogFactory.getLog( DateUtil.class );

    private static final String TIME_PATTERN = "HH:mm";

    /**
     * Checkstyle rule: utility classes should not have public constructor
     */
    private DateUtil()
    {
    }

    /**
     * Return default datePattern (MM/dd/yyyy)
     * @return a string representing the date pattern on the UI
     */
    public static String getDatePattern()
    {
        Locale locale = LocaleContextHolder.getLocale();
        String defaultDatePattern;
        try
        {
            defaultDatePattern = ResourceBundle.getBundle( Constants.BUNDLE_KEY, locale ).getString( "date.format" );
        }
        catch ( MissingResourceException mse )
        {
            defaultDatePattern = "MM/dd/yyyy";
        }

        return defaultDatePattern;
    }

    public static String getDateTimePattern()
    {
        return DateUtil.getDatePattern() + " HH:mm:ss.S";
    }

    /**
     * This method attempts to convert an Oracle-formatted date
     * in the form dd-MMM-yyyy to mm/dd/yyyy.
     *
     * @param aDate date from database as a string
     * @return formatted string for the ui
     */
    public static String getDate( Date aDate )
    {
        SimpleDateFormat df;
        String returnValue = "";

        if ( aDate != null )
        {
            df = new SimpleDateFormat( getDatePattern() );
            returnValue = df.format( aDate );
        }

        return ( returnValue );
    }

    /**
     * This method generates a string representation of a date/time
     * in the format you specify on input
     *
     * @param aMask the date pattern the string is in
     * @param strDate a string representation of a date
     * @return a converted Date object
     * @see java.text.SimpleDateFormat
     * @throws ParseException when String doesn't match the expected format
     */
    public static Date convertStringToDate( String aMask, String strDate )
        throws ParseException
    {
        SimpleDateFormat df;
        Date date;
        df = new SimpleDateFormat( aMask );

        if ( log.isDebugEnabled() )
        {
            log.debug( "converting '" + strDate + "' to date with mask '" + aMask + "'" );
        }

        try
        {
            date = df.parse( strDate );
        }
        catch ( ParseException pe )
        {
            //log.error("ParseException: " + pe);
            throw new ParseException( pe.getMessage(), pe.getErrorOffset() );
        }

        return ( date );
    }

    /**
     * This method returns the current date time in the format:
     * MM/dd/yyyy HH:MM a
     *
     * @param theTime the current time
     * @return the current date/time
     */
    public static String getTimeNow( Date theTime )
    {
        return getDateTime( TIME_PATTERN, theTime );
    }

    /**
     * This method returns the current date in the format: MM/dd/yyyy
     * 
     * @return the current date
     * @throws ParseException when String doesn't match the expected format
     */
    public static Calendar getToday()
        throws ParseException
    {
        Date today = new Date();
        SimpleDateFormat df = new SimpleDateFormat( getDatePattern() );

        // This seems like quite a hack (date -> string -> date),
        // but it works ;-)
        String todayAsString = df.format( today );
        Calendar cal = new GregorianCalendar();
        cal.setTime( convertStringToDate( todayAsString ) );

        return cal;
    }

    /**
     * This method generates a string representation of a date's date/time
     * in the format you specify on input
     *
     * @param aMask the date pattern the string is in
     * @param aDate a date object
     * @return a formatted string representation of the date
     * 
     * @see java.text.SimpleDateFormat
     */
    public static String getDateTime( String aMask, Date aDate )
    {
        SimpleDateFormat df = null;
        String returnValue = "";

        if ( aDate == null )
        {
            log.error( "aDate is null!" );
        }
        else
        {
            df = new SimpleDateFormat( aMask );
            returnValue = df.format( aDate );
        }

        return ( returnValue );
    }

    /**
     * This method generates a string representation of a date based
     * on the System Property 'dateFormat'
     * in the format you specify on input
     * 
     * @param aDate A date to convert
     * @return a string representation of the date
     */
    public static String convertDateToString( Date aDate )
    {
        return getDateTime( getDatePattern(), aDate );
    }

    /**
     * This method converts a String to a date using the datePattern
     * 
     * @param strDate the date to convert (in format MM/dd/yyyy)
     * @return a date object
     * @throws ParseException when String doesn't match the expected format
     */
    public static Date convertStringToDate( String strDate )
        throws ParseException
    {
        Date aDate = null;

        try
        {
            if ( log.isDebugEnabled() )
            {
                log.debug( "converting date with pattern: " + getDatePattern() );
            }

            aDate = convertStringToDate( getDatePattern(), strDate );
        }
        catch ( ParseException pe )
        {
            log.error( "Could not convert '" + strDate + "' to a date, throwing exception" );
            pe.printStackTrace();
            throw new ParseException( pe.getMessage(), pe.getErrorOffset() );
        }

        return aDate;
    }
}
